Gender differences in executive functions and reading abilities in children with attention deficit hyperactivity disorder

Background
Executive function (EF) develops throughout childhood and adolescence. Up to half of youth with attention deficit hyperactivity disorder (ADHD) show executive dysfunction. Reading disability has a comorbidity with ADHD of 20–40%. Adequate reading comprehension depends on higher cognitive skills beyond word decoding.
Aim
The aim of this study was to investigate EFs and reading abilities in a group of primary school children with ADHD [intelligence quotient (IQ)≥85] and whether they differ with sex.
Methods
A total of 30 Egyptian boys and 30 girls aged 8–12 years diagnosed with ADHD were compared with 40 healthy matched controls in terms of clinical assessment of reading skills, comorbidites, IQ, ADHD symptoms using Conners’ Parent Rating Scale-Revised-Long version (CPRS-R-L), EFs using the Wisconsin Card Sorting Test (WCST), and metacognitive reading using the Metacognitive Reading Comprehension Scale.
Results
In total, 50% of ADHD cases showed the combined type, 31.7% the predominantly inattentive, and 18.3% the predominantly hyperactive type, with a significant gender difference (=0.007). Patients had significantly higher scores in all CPRS-R-L scales, except for the anxious–shy subscale. Boys had higher means in the ‘hyperactivity’, whereas girls had higher means in the ‘cognitive problems/inattention’ scale. Male and female patients did not differ in comorbid learning disabilities but differed in conduct disorder and depression. Patients scored significantly lower on all WCST indices, except the first trials (<0.001). Girls with ADHD made more errors, =0.050, and completed less number of categories than boys, =0.024. EF did not correlate with the hyperactivity subscale of CPRS-R-L. It correlated with the cognitive problems/inattention subscale in male and female patients. The Metacognitive Reading Comprehension scores differed significantly between the children with ADHD and the controls (<0.001). None of the WCST indices predicted the Metacognitive Reading Comprehension total score. The total score was predicted only by the CPRS-R-L N scale (DSM-IV total), but not by its other subscales, IQ scales, sex, or age.
Conclusion
Children with ADHD have lower EF and reading abilities than controls. Executive dysfunction is related to inattention and not to hyperactivity. No robust differences in EF can be attributed solely to sex. Reading and metacognitive reading dysfunctions showed no gender difference.